US6595231B1 - Device and method for regulating the pressure of a gas stream - Google Patents
Device and method for regulating the pressure of a gas stream Download PDFInfo
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- US6595231B1 US6595231B1 US09/868,056 US86805601A US6595231B1 US 6595231 B1 US6595231 B1 US 6595231B1 US 86805601 A US86805601 A US 86805601A US 6595231 B1 US6595231 B1 US 6595231B1
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- pressure
- diaphragm
- chamber
- control chamber
- gas stream
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D16/00—Control of fluid pressure
- G05D16/20—Control of fluid pressure characterised by the use of electric means
- G05D16/2093—Control of fluid pressure characterised by the use of electric means with combination of electric and non-electric auxiliary power
- G05D16/2095—Control of fluid pressure characterised by the use of electric means with combination of electric and non-electric auxiliary power using membranes within the main valve
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/0318—Processes
- Y10T137/0396—Involving pressure control
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/2496—Self-proportioning or correlating systems
- Y10T137/2559—Self-controlled branched flow systems
- Y10T137/2574—Bypass or relief controlled by main line fluid condition
- Y10T137/2605—Pressure responsive
- Y10T137/2607—With pressure reducing inlet valve
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/7722—Line condition change responsive valves
- Y10T137/7758—Pilot or servo controlled
- Y10T137/7761—Electrically actuated valve
Definitions
- the present invention relates to a device for regulating the pressure and/or the flow of a gas stream, which device comprises a housing which is provided with a pressure-regulating chamber, at least part of whose wall comprises a diaphragm, which diaphragm is subjected, on the side remote from the pressure-regulating chamber, to an adjustable prestressing force, the pressure-regulating chamber comprising an inlet opening for a gas and an outlet opening for a gas, it being possible for at least one of the openings to be completely or partially closed off with the aid of the diaphragm.
- the extent to which the diaphragm bends is dependent, on the one hand, on the instantaneous pressure in the pressure-regulating chamber and, on the other hand, on the stress which is applied to the diaphragm with the aid of the prestressing means, wherein the diaphragm is actively connected to a pressure chamber for a gas, which pressure chamber is provided with has an inlet opening for a gas and an outlet opening for a gas for setting the pressure in the pressure chamber for the purpose of applying the prestressing force.
- a device of the abovementioned type is known in the prior art.
- the device may be used, for example, to regulate a gas stream which is at a relatively high pressure down to a gas stream at a lower pressure.
- the position of the closure member is linked to the bending of the diaphragm. Consequently, the pressure of the gas stream which leaves the pressure-regulating chamber via the outlet opening will be determined by the position of the diaphragm in a starting position.
- the known device can be used to reduce the pressure of a gas stream to a desired level.
- the pressure of the gas stream which will leave the pressure-regulating chamber at the outlet opening will be dependent on the size of the inlet opening which is left open by the closure member. The more the closure member closes off the inlet opening, the lower the pressure flowing out of the outlet opening of the pressure-regulating chamber will be.
- the above mentioned device is (i.a.) known from U.S. Pat. No. 4,798,521. From this document a device is known for regulating the pressure in a container. In addition to the mentioned elements, the known device comprises means for measuring possible differences in the pressure in the pressure chamber and the device's outlet opening, which differences can used for regulating the pressure in the pressure chamber.
- the object of the present invention is to provide a device of the type mentioned in the introduction with which it is possible to accurately set the position of the diaphragm. It is also desirable for it to be possible to adjust a position of the diaphragm once it has been set, in a relatively simple manner.
- inlet opening is provided with a flow restriction.
- outlet opening is provided with a flow restriction.
- a pressure chamber in which a gas is kept under pressure allows the position of the diaphragm in the starting position, and therefore the position of the closure member in the inlet opening of the pressure-regulating chamber, to be adjusted with the aid of a gas pressure.
- the position of the diaphragm can be fixed as desired.
- the side of the diaphragm which is remote from the pressure-regulating chamber adjoins the pressure chamber.
- the inlet opening and the outlet opening of the pressure chamber are provided with a remotely controllable shut-off valve.
- the position of the diaphragm can be altered by altering the pressure in the pressure-regulating chamber.
- the remotely controllable shut-off valves allow the setting of the pressure in the pressure-regulating chamber to be coupled, for example, to measuring means which are accommodated elsewhere in the device.
- the device it is possible for the device to be provided with means for measuring the pressure of the gas stream, which measuring means are arranged in the vicinity of the outlet opening of the pressure-regulating chamber. It is also possible for the device to be provided with means for measuring the pressure of the gas stream, which measuring means are arranged in the vicinity of the inlet opening of the pressure-regulating chamber. In this case, it is advantageous for the device to be provided with regulating means which are actively connected to, on the one hand, the means for measuring the gas pressure and, on the other hand, the remotely controllable shut-off valves of the pressure chamber.
- the diaphragm is also possible for the diaphragm to be connected, via a coupling member, to a second diaphragm, the said second diaphragm adjoining the pressure chamber, and that side of the diaphragm which is remote from the pressure-regulating chamber adjoining a second pressure chamber, the pressure-regulating chamber being in communication, via a restriction, with a feed line for a gas, and the second pressure-regulating chamber being in open communication with the said feed line.
- This measure allows the present invention to be used for setting a diaphragm, with both its sides adjoining a feed line for a gas stream.
- the first side of the diaphragm adjoins a closed space which contains an outlet opening and is connected to the feed line via a restriction.
- the other side of the diaphragm adjoins a closed space which is in free communication with the feed line. If flow takes place from the feed line, via the restriction, to the outlet opening of the closed space on the first side of the diaphragm, the presence of the restriction will cause there to be a pressure difference across the diaphragm. This pressure difference determines the position of the diaphragm and hence the extent to which the outlet opening is closed off.
- the equilibrium position about which the diaphragm will move can be set, by means of the measures described above, with the aid of the said pressure chamber, it being possible to vary the pressure in the pressure chamber.
- At least one wall of the pressure chamber is formed by a second diaphragm which is connected, via a coupling member, to the diaphragm which is connected on both sides to the feed line.
- the present invention also relates to a gas chromatograph provided with the above mentioned device.
- the device according to the present invention is especially suited to be used in a gas chromatograph. Firstly because at both sides of the diaphragm a gas is present, diffusion through the material of the diaphragm will be limited to a minimum. Further it is possible to connect both the inlet opening of the pressure-regulating chamber and the inlet opening of the pressure chamber to one and the same feed line. That means that on both sides of the diaphragm the same gas will be present. In the gas chromatograph it is possible to add a substance to be examined to the gas flow when the pressure of the gas flow has been decreased from a relatively high pressure to a relatively low pressure, i.e. downstream of the device according to the present invention. The result of this will be that possible loss of material to be examined will be prevented.
- the present invention relates to a method for regulating the pressure or a flow of a gas stream, in which the gas stream to be regulated is fed from an inlet chamber, via an inlet opening, to a pressure-regulating chamber, at least part of whose wall is formed by a diaphragm, the pressure in the pressure-regulating chamber being regulated by adjusting the size of the inlet opening of the pressure-regulating chamber with the aid of a closure member which is actively connected to the diaphragm in such a manner that a change in the level of displacement of the diaphragm causes a change to the extent to which the closure member closes off the inlet opening, the diaphragm being subjected to a prestressing force, with the aid of which a specific positioning is imposed on the diaphragm.
- the method according to this invention is characterized in that the said prestressing force is applied by a pressurized gas in the pressure chamber, the starting position of the diaphragm being set by setting the pressure of the gas in the pressure chamber.
- the gas stream it is possible for the gas stream to be discharged from an outlet opening of the pressure-regulating chamber.
- the pressure of the gas stream it is advantageous for the pressure of the gas stream to be measured at least periodically in the vicinity of the outlet opening of the pressure-regulating chamber, and for the measured value to be compared with a desired value which is dependent on the starting position of the diaphragm, and for the pressure in the pressure chamber to be increased or reduced on the basis of this comparison by feeding or discharging gas to or from the pressure chamber.
- the device is designed in such a way that any deviations from the desired pressure in the gas stream emerging from the pressure-regulating chamber caused by variations in the position of the diaphragm can be eliminated by the device itself. Any undesirable residual variations can be effectively eliminated by means of the method according to the invention.
- a volume of gas to be fed to the pressure chamber, during or after which process a different volume of gas is discharged from the pressure chamber.
- the pressure in the pressure chamber is allowed to gradually increase or decrease.
- the pressure of the gas stream which leaves the pressure-regulating chamber may be advantageous to allow the pressure of the gas stream which leaves the pressure-regulating chamber to gradually increase or decrease.
- a gas chromatograph it may be that in the event of variations in pressure, different elements are separated out of the gas stream in a column which may be positioned in a line which is connected to the device according to the present invention. If the pressure in the pressure chamber is now gradually varied, the pressure of the gas stream leaving the pressure-regulating chamber will also vary. These variations may benefit the separating capacity of the column.
- FIG. 1 shows a device for regulating the pressure or the flow of the gas stream according to the prior art
- FIG. 2 shows a device for regulating the pressure in a gas stream according to a preferred design
- FIG. 3 shows a diagrammatic overview of a gas chromatograph in which the device according to the present invention is arranged
- FIG. 4 shows a diagrammatic overview of possible input and output parameters of a pressure control computer useful in the gas chromatograph illustrated in FIG. 3;
- FIG. 5 diagrammatically shows the feed of a gas stream to the pressure chamber
- FIG. 6 shows a possible embodiment of the device according to the present invention, in a miniaturized form
- FIG. 8 is a schematic view of the operation of a pressure control module useful in the gas chromatograph illustrated in FIG. 3;
- FIG. 9 is a schematic view of the operation of a fuzzy pressure controller useful in the gas chromatograph illustrated in FIG. 3.
- FIG. 10 shows a possible variant design of the device according to the present invention.
- FIG. 1 shows a device 1 by means of which it is possible to regulate the pressure of a gas stream.
- the device in accordance with FIG. 1 is known in the prior art.
- the device in accordance with FIG. 1 comprises a gas inlet chamber 2 which is connected, via an inlet opening 3 , to a pressure-regulating chamber 4 .
- this pressure-regulating chamber also comprises an outlet opening 5 .
- the inlet chamber 2 forms a passage which is provided with means 6 for connecting a gas line, for example.
- the means 6 may, for example, comprise a nut.
- the outlet opening 5 of the pressure-regulating chamber 4 is connected to a passage 7 which is provided with means 8 for connection of a gas line, for example.
- the pressure-regulating chamber 4 is closed off by means of a flexible member or diaphragm 10 .
- the diaphragm 10 On its top side, the diaphragm 10 is connected to a spring 11 .
- the spring 11 can be used to apply a stressing force to the diaphragm 10 .
- the extent of the stressing force exerted by the spring 11 on the diaphragm 10 is dependent on the setting of the setscrew 12 which is actively connected to the top side (in the position shown in the figure) of the spring 11 .
- the diaphragm 10 is connected to a closure member 15 .
- the closure member 15 is coupled to the diaphragm 10 in such a manner that the position of the closure member 15 is dependent on the bending of the diaphragm 10 .
- closure member 15 is connected, on the underside, to a spring 17 .
- This spring 17 ensures that the closure member 15 is positioned correctly in the outlet opening 3 of the pressure-regulating chamber by the interaction of the diaphragm 10 and the spring 17 .
- the device 1 operates as follows:
- the setscrew 12 and the spring 11 are used to set a specific spring pressure on the diaphragm 10 .
- the spring pressure acting on the diaphragm 10 sets the position of the closure member 15 in the feed opening 3 .
- the inlet chamber 2 is connected to a relatively high-pressure line.
- the discharge opening 5 can be connected to a line in which it is desired to have a gas stream at a constant pressure.
- the gas stream from the inlet chamber 2 to the pressure-regulating chamber 4 will exert a pressure on the underside of the diaphragm 10 .
- the higher the pressure in the pressure-regulating chamber 10 becomes the greater the distance between the diaphragm 10 and the inlet opening 3 of the pressure-regulating chamber 4 will be.
- the closure member 15 will be pulled upwards, so that the inlet opening 3 will be closed off further. Since the passage is closed off further, the gas stream from the inlet chamber 2 to the pressure-regulating chamber 4 will decrease. As a result, the pressure in the pressure-regulating chamber 4 will fall, with the result that the diaphragm 10 will move slightly downwards.
- the device 1 for regulating the pressure of a gas stream according to the prior art can be used in a gas chromatograph.
- a chromatograph of this nature it is important that it is possible for the gas stream which is to be analyzed to be forced through a column, for example, at a pressure which is easy to set and constant.
- the device 1 according to the prior art is therefore installed in the feed line of a column of this nature.
- a significant drawback of the device 1 according to the prior art is that it is necessary for a pressure to be continuously exerted on the diaphragm 10 with the aid of the spring 11 . Moreover, the diaphragm 10 cannot be accurately set with the aid of the spring 11 and the setscrew 12 . A further drawback is that the diaphragm 10 may cause diffusion to occur. Pressurized gas will be present in the pressure-regulating chamber 4 . Depending on the material of the diaphragm 10 , it is possible that certain components of the gas in the pressure-regulating chamber 4 may diffuse through the diaphragm 10 . This means that these constituents will disappear from the gas stream and will not leave the pressure-regulating chamber via the outlet opening 5 . If the device 1 according to the prior art is used, for example, for a gas chromatograph, the occurrence of diffusion may mean that the measurements taken will be unreliable.
- FIG. 2 shows an exemplary embodiment of the device 20 for regulating the pressure of a gas stream according to the present invention.
- the device 20 comprises a housing 9 in which an inlet chamber 2 is incorporated. Via an inlet opening 3 , this inlet chamber 2 is connected to the pressure-regulating chamber 4 . On its top side (in the position shown in the figure), the pressure-regulating chamber 4 is closed off by means of a flexible member 10 .
- the pressure-regulating chamber 4 is connected to a passage 7 via an outlet opening 5 .
- the inlet chamber 2 can be connected to a connection line for a gas, for example, with the aid of connection means 6 . With the aid of connection means 8 , passage 7 can be connected to, for example, a discharge line for gas.
- the device according to the present invention comprises a pressure chamber 21 .
- This pressure chamber 21 comprises an inlet opening 22 and an outlet opening 23 .
- the inlet opening 22 and the outlet opening 23 can be connected to a feed line 24 for gas and a discharge line 25 for a gas, respectively.
- Remotely controllable closure members 26 and 27 may be arranged in the lines 24 and 25 , respectively.
- measuring means 30 which can be used to measure the pressure of the gas in the vicinity of the outlet opening 5 , are arranged in the vicinity of the outlet opening 5 .
- These pressure-measuring means 30 are actively connected to a control unit 31 .
- This control unit may, for example, contain features which compare the values measured by the means 30 with desired or set values.
- the control unit 31 is in turn actively connected to the remotely controllable shut-off valves 26 and 27 .
- the device 20 functions as follows:
- a gas line containing a gas which is at a relatively high pressure can be connected to the inlet chamber 2 .
- a discharge line for discharging a gas can be attached to the passage 7 .
- the gas flows towards the pressure-regulating chamber 4 via the inlet chamber 2 and the inlet opening 3 .
- the gas stream then leaves the pressure-regulating chamber 4 via the outlet opening 5 in the passage 7 .
- the inlet opening 3 can be closed off with the aid of a closure member 15 which is actively connected to the diaphragm 10 .
- an equilibrium pressure and therefore an equilibrium flow, will be automatically built up in the pressure-regulating chamber 4 .
- a gas stream which is at an essentially constant pressure will leave the pressure-regulating chamber 4 via the outlet opening 5 .
- the equilibrium level of the pressure which is set in the pressure-regulating chamber 4 is not dependent on a spring pressure, but rather on a pressure which is built up in a pressure chamber 21 on the opposite side of the diaphragm 10 .
- the pressure of the diaphragm 10 is essentially determined, on the one hand, by the pressure in the pressure-regulating chamber 4 and, on the other hand, by the pressure in the pressure chamber 21 .
- the pressure chamber 21 is provided with an inlet opening 22 and an outlet opening 23 .
- the inlet opening 22 may also be connected to a gas line 24 .
- a closure member 26 may be arranged in this gas line 24 .
- a similar arrangement applies to the outlet opening 23 , to which a gas line 25 can be coupled.
- a closure member 27 can be arranged in this gas line 25 .
- shut-off valves 26 and 27 can be opened and closed as desired and gas can be fed to or discharged from the pressure chamber 21 with the aid of the lines 24 and 25 .
- the pressure of the gas which prevails in the discharge passage 7 will be periodically or continuously measured with the aid of the measuring means 30 .
- This measurement information will be transmitted to the control unit 31 .
- the control unit 31 is actively connected to the shut-off valves 26 and 27 in the lines 24 and 25 . If, for example, it is established by the measuring means 30 that the pressure of the gas which is flowing out of the pressure-regulating chamber 4 is too high, the pressure in the pressure chamber 21 can be reduced by opening the shut-off valve 27 in the line 25 for a certain time. As a result, gas will be able to escape from the pressure chamber 21 , with the result that a new equilibrium pressure can be established in the pressure-regulating chamber 4 .
- discharge line 25 is generally able to flow out freely to the environment.
- the advantage of the device 20 according to the present invention is that the position of the diaphragm 10 can be adjusted with a relatively high degree of accuracy. If desired, the gas feed via the inlet opening 22 of the pressure chamber 21 can be used to feed gas until the correct pressure is reached in the pressure-regulating chamber 4 . In this case, the periodic measurement of the pressure in the discharge passage 7 can be used as an input signal for adjusting the pressure in the pressure chamber 21 .
- An additional advantage is that the pressure in the pressure chamber 21 can be changed, for example periodically or gradually.
- Applications are known, for example in the case of gas chromatographs, in which it is advantageous if the pressure of the gas stream which is fed to a chromatograph increases or decreases, for example.
- the detection means which are generally coupled to the column which is used in a chromatograph (not shown).
- FIG. 3 diagrammatically depicts the use of a device 20 according to the invention which is employed in a gas chromatograph.
- a gas stream is fed towards the inlet chamber 2 .
- the inlet chamber 2 can be closed off from the pressure-regulating chamber 4 with the aid of the closure member 15 .
- the pressure which is built up in the pressure-regulating chamber 4 on the underside of the diaphragm 10 and the pressure which is built up in the pressure chamber 21 on the top side of the diaphragm 10 together determine the position of the diaphragm 10 , and hence the position of the closure member 15 in the inlet opening 3 between the inlet chamber 2 and the pressure-regulating chamber 4 .
- a gas stream which is at an essentially constant pressure will flow through the passage 7 . Since a constant pressure is ensured, the volume of the flow will also be constant.
- This stream which is at an essentially constant pressure is fed from the passage 7 towards an injector 32 .
- the gas stream is fed, for example, to a column chroinatograph which is diagrammatically indicated by 33 .
- This column chromatograph may, for example, comprise a coiled glass tube in which a separating medium is arranged.
- the gas stream emerging from the column is then fed to detection means which are diagrammatically indicated by 34 .
- the detection means may be coupled to a processing unit, such as a PC 35 .
- This PC may also serve, for example, to control the temperature regulation of the chromatograph. This is diagrammatically indicated by the line T.
- the PC 35 can also be used to control the control unit 31 which is used to regulate the pressure in the pressure chamber 21 .
- the pressure in the pressure-regulating chamber 20 is regulated as described with reference to FIG. 2 .
- FIG. 3 further shows that the pressure regulating chamber 4 is provided with a valve for relieving the pressure, pressure relief valve 72 .
- the path at the output of pressure-regulating chamber 4 sometimes exhibits a high flow restriction, attrubutable to the presence of a long column having a small internal diameter. Because of this high (flow) restriction the speed for regulating from a relatively high pressure to a relatively low pressure is limited.
- Pressure relief valve 72 enables a part of the redundant gas flow, to be released through flow restriction 70 .
- Pressure relief valve 72 also serves as a pressure safety valve. When because of malfunctioning or leakage the pressure in the pressure regulating chamber 4 is too high, the control unit 31 will react, by opening pressure relief valve 72 . Therefore, possible damage to the system can be prevented.
- FIG. 3 shows, that the inlet which is connected to the inlet chamber 2 is the same as the inlet connected to the valve 26 . That mean that the gas that is being used for regulating the pressures in both the chamber 4 and 21 comes from the same source.
- a gas chromatograph When used as a gas chromatograph normally a stable gas flow is established, before adding the medium to be examined to the gasflow, upstream of the column.
- FIG. 3 it shows that between the respective valve 26 and 27 and the pressure chamber 21 flowrestrictions 41 , 42 are present.
- These valves have at least a certain minimal switching time, therefore it is possible that when the valves are opened an amount of gas is being transported through the valve that, in respect of the volume of the pressure chamber, is too large in order to obtain the preferred control characteristics.
- a so called “padding” (not shown) can be used.
- This padding can be positioned inside the opening of the valve connected to the inlet opening or oulet opening of the pressure chamber. Because of the presence of the padding the volume between the valve sealing and the restriction can be partially filled. Therefore, even a smaller amount of gas having a relatively high pressure will be transported through the valve, thereby increasing the accuracy of the pressure control.
- the regulating arrangement illustrated in FIG. 4 5 can be used to avoid this “dead space” being formed. If the pressure in the pressure chamber 21 is to be increased, a relatively large volume of gas is fed into the pressure chamber via the shut-off valve 26 . This is indicated by the line IN. At the same time, a slightly smaller volume of gas is released from the pressure chamber 21 via the shut-off valve 27 . This is indicated by the line OUT. The net result is that a relatively small volume of gas will be fed to the pressure chamber 21 . This is indicated by the line IN (RESULT).
- a restriction 41 is arranged between the shut-off valve 26 and the inlet opening of the pressure chamber 21 .
- a similar restriction 42 is also arranged between the outlet opening of the pressure chamber 21 and the shut-off valve 27 .
- These restrictions 41 and 42 are to be regarded as “delay means” for the gas stream.
- This retention member may be likened to a resistor in an electrical line.
- the restrictions 41 and 42 may, for example, be formed by sintered material. The gas stream is allowed through but delayed by a porous, spongy structure of the sintered material.
- FIG. 4 depicts which parameters will be fed to the “pressure control computer”, PC 35 , shown in FIG. 3 .
- the incoming signals e.g. can be used for the flow set, the gas viscosity, the pressure out, the ambient pressure, the diameter and length of the column connected to the pressure-regulating chamber 4 and/or the set oven temperature. All these parameters can be forwarded to the “pressure control computer”, PC 35 , which sends signals to the control valves subsequently to establish the required pressure (Pset).
- the device 20 according to the present invention is suitable in particular for very small applications.
- the design of the device 20 means that it can be miniaturized relatively easily.
- One exemplary embodiment is a device 20 made of silicon, for example, using etching techniques.
- the inlet chamber 2 is situated on the top side of the diaphragm 10 .
- the lines illustrated in the figure will in practice have a thickness of a few ⁇ m.
- the pressure chamber 21 is situated on the underside of the diaphragm 10 in the device 20 .
- the shut-off valves 26 and 27 are respectively formed by flexible closure lips which are shown on the left and right in the figure.
- the present invention refers to the use of the device 20 according to the present invention for forming a stream of gas which is at an essentially constant pressure from a feed gas stream which is at a relatively high pressure.
- the structure which has already been discussed with reference to the figures mentioned above may, however, also be employed, with a minor adaptation, as back pressure regulator.
- the position of the diaphragm 10 is determined by the pressure which prevails in both the pressure-regulating chamber 4 and the pressure chamber 21 .
- the description of the figures mentioned above refers to the opening between the passage 2 and the pressure-regulating chamber 4 decreasing in size as the pressure in the pressure-regulating chamber 4 increases. It can be seen from FIG. 6 7 that in the device 60 , which is intended to regulate a back pressure regulator, the outlet opening 29 between the pressure-regulating chamber 4 and the passage 2 increases in size as the pressure in the pressure-regulating chamber 4 increases. In practice, this will mean that when a gas stream is supplied via the passage 7 and the outlet opening 28 , this gas stream can be fed to the pressure-regulating chamber 4 at an essentially constant pressure and with an essentially constant flow.
- the device 60 is equipped with measuring means 30 , which can be used to measure the pressure of the gas stream in the passage 7 . These measuring means 30 are actively connected to the control means 31 , with the aid of which the shut-off valves 26 , 27 can be operated.
- FIG. 8 schematically the outlook over the pressure control computer is shown, which can be used in the device and the method according to the present invention.
- the pressure control computer is provided with electronics, such as a single chip micro controller and a high resolution A/D converter.
- the micro controller can by means of a serial interface communicate with any other instrument. By means of interface, parameters for pressure control can be set and the actual value of the pressure can be established. Every pressure control computer can monitor several pressure controls, completely independently. Moreover every pressure control computer has a known address, therefore several modules can be monitored in parallel by means of the same ire interface.
- the values for calibration of the pressure sensors can be forwarded to the pressure control computer and automatically the off-set-values are determined.
- This calibration can be executed with reference to any reference-pressure. In the software these values can be used to correct the off-set automatically and to calculate the right pressure values.
- the software present in the pressure control computer comprises a control algorithm, based on the use of fuzzy logic.
- fuzzy pressure controller As inputs for the fuzzy pressure controller (FPC) both the absolute variation of the actual pressure with respect to the said point and the speed of the pressure change can be used. Also other inputs such as the ambient temperature and the ambient pressure can be used as an input.
- the output of the fuzzy pressure controller determines how the valve should be controlled.
- the advantage of the fuzzy pressure controller is that it is not necessary to make a mathematical model of the behaviour of the device and the influence of the valves in the entire pressure-range. Building such a mathematical model in practice is very awkward, because the model strongly depends of on the ambient conditions, the actual work pressure ends the variable restrictions in the system.
- the fuzzy pressure controller is based on the fact that both the measured values and the set values will be divided by intervals, which overflow. By means of a fuzzy rule base the measured values will be examined and the right value for correction will be generated, wherein the fuzzy pressure controller will be working in a fully adaptive mode.
- FIG. 9 This is schematically shown in FIG. 9 .
- the fuzzy pressure controller is shown, being connected to a fuzzy rule base.
- input signals of the fuzzy pressure controller are used the actual pressure and the pressure setpoints.
- an other input is also possible.
- a correction-output is sent to a valve controller. From this value, signals are forwarded for correctly controlling the valves.
- the fuzzy process controller uses besides the input and output valve also a so-called vent valve or pressure relief valve.
- This vent valve is an extra outlet opening and can be used to quickly decrease the pressure.
- the vent valve is controlled by the fuzzy pressure controller, when the difference in the set values, the set point and the actual pressure exceeds a certain value.
- the fuzzy process controller comprises an internal safety, which prevents that the pressure can exceed a certain critical value. As soon as an actual pressure is detected above the maximum acceptable pressure, the outlet opening and the vent valve are opened for quickly decreasing the pressure. This is necessary for protecting the downstream system.
- the pressure control module can work stand alone and take care of a programmed and constant flow regulation.
- the several parameters for the pressure regulation can be read from a known memory or can be introduced by means of a serial interface.
- the required pressure profile can automatically or by means of an external interface be started. This means that in combination with the pressure regulating device as described above a “stand-alone” unit can be created, forming a universally usable pressure-flow regulator.
- FIG. 10 shows a device 100 which can be used to regulate the flow of a gas stream.
- the first diaphragm 110 is positioned between a second pressure chamber 112 and a pressure-regulating chamber or flow chamber 104 .
- the flow chamber 104 and the second pressure chamber 112 are both connected to a feed line 107 for a gas stream.
- the second pressure chamber 112 is in open communication with this feed line 107 .
- Via a restriction 108 the flow opening of the flow chamber 104 is connected to the feed line 107 .
- the flow chamber 104 has an outlet opening 109 , which can be closed off with the aid of a member 115 , and an inlet opening 128 .
- the equilibrium position of the member 115 which is coupled to the diaphragm 110 via a coupling piece 116 , can be set with the aid of a second diaphragm 111 .
- This second diaphragm 111 is connected to the outer wall of the second pressure chamber 112 with the aid of a spring 118 and to diaphragm 110 by member 115 .
- the second diaphragm 111 forms a wall of a pressure chamber 121 .
- the pressure in this pressure chamber 121 can be regulated by selectively allowing gas to flow into the pressure chamber 121 via the shut-off valve 126 and the inlet opening 122 or by allowing gas to escape from the pressure chamber 121 via the outlet opening 123 and the shut-off valve 127 .
- the equilibrium position of the member 115 which is attached to the diaphragm 110 is determined as a function of the pressure in the pressure camber 121 .
- a pressure gauge 130 is arranged in the feed line 107 .
- This pressure gauge 130 is actively connected to a control unit 131 .
- This control unit 131 in turn controls the shut-off valves 126 and 127 .
- the devices 20 , 60 , 100 discussed above are particularly suitable for portable chromatographs. The reason for this is that the devices do not require much power. Power is only required to change the setpoint of the devices, in which event power will be required in order to be able to cause gas to flow into or be discharged from pressure chamber 21 . Therefore, there is no need for a constant current in order to keep the diaphragm 10 in position.
- valves in principle are closed. Only when regulating is necessary, i.e. when the pressure in the pressure chamber has to be amended, energy is needed for actuating the valves. That means that the system is able to function with low energy consumption.
- a further advantage of the above mentioned device is that the valve in principle are closed. Only when regulating is nessecary, i.e. when the pressure in the pressure chamber has to be amended, energy is needed for actuating the valves. That means that the system is able to function with low-energy consumption.
- the device 20 , 60 , 100 according to the present invention will be suitable for gas streams of from 0.1 ml to 100 ml per minute.
- the volume of injection gas used may be 20 microlitres per minute.
- the devices 20 , 60 , 100 operate via a cascade arrangement.
- the mechanism by which the shut-off valve 15 is mechanically connected to the diaphragm 10 means that adjustment of the opening between the inlet passage 2 and the pressure turbulence chamber 4 will entail an analogue regulation which adjusts itself automatically about an equilibrium value. This equilibrium value itself can be set with the aid of the measuring means 31 which are able to control the shut-off valves 26 and 27 .
- the accuracy of a pressure regulator is equal to that of the pressure sensor itself. Due to the analogue regulation of the pressure in the pressure-regulating chamber 4 , the device 20 . 60 , 100 is much more accurate.
- the resolution which is usual in the prior art is ⁇ 1 kPa.
- the device 20 , 60 , 100 makes it possible to achieve a resolution of 1/100 kPa.
- the setpoint can be set with a similar degree of accuracy. Owing to the analogue control of the device itself, the. device will be automatically regulated about the setpoint with an accuracy which may reach a level of 1/100 kPa.
- One of the additional advantages of the device 20 , 60 according to the present invention is that maintaining a gas pressure on both sides of the diaphragm allows diffusion of the gas through the diaphragm to be limited to a minimum. If the same pressurized gas is maintained on both sides of the diaphragm, there will be no diffusion.
- a suitable material for the diaphragm may, for example, be silicone rubber.
- the diaphragm may be of slightly concave design.
Abstract
Description
Claims (31)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL1010815 | 1998-12-15 | ||
NL1010815A NL1010815C2 (en) | 1998-12-15 | 1998-12-15 | Apparatus and method for controlling the pressure of a gas flow. |
PCT/NL1999/000773 WO2000036482A1 (en) | 1998-12-15 | 1999-12-15 | Device and method for regulating the pressure of a gas stream |
Publications (1)
Publication Number | Publication Date |
---|---|
US6595231B1 true US6595231B1 (en) | 2003-07-22 |
Family
ID=19768316
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/868,056 Expired - Lifetime US6595231B1 (en) | 1998-12-15 | 1999-12-15 | Device and method for regulating the pressure of a gas stream |
Country Status (7)
Country | Link |
---|---|
US (1) | US6595231B1 (en) |
EP (1) | EP1151364B1 (en) |
JP (1) | JP2002532800A (en) |
AU (1) | AU1897300A (en) |
DE (1) | DE69915374T2 (en) |
NL (1) | NL1010815C2 (en) |
WO (1) | WO2000036482A1 (en) |
Cited By (11)
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US20040182148A1 (en) * | 2003-03-19 | 2004-09-23 | Smith John A. | Method and apparatus for conditioning a gas flow to improve a rate of pressure change measurement |
US20050279408A1 (en) * | 2004-06-18 | 2005-12-22 | Henderson Robert C | Electronically controlled back pressure regulator |
WO2007131346A1 (en) * | 2006-05-11 | 2007-11-22 | Delaney Machinerie Inc. | Pressure controller device |
GB2447862A (en) * | 2007-03-24 | 2008-10-01 | Schlumberger Holdings | Control valve |
US20100090137A1 (en) * | 2008-10-10 | 2010-04-15 | Ckd Corporation | Flow rate control device |
US20100108923A1 (en) * | 2008-11-04 | 2010-05-06 | Abb Technology Ag | Electropneumatic transducer with a pneumatic pressure-regulating valve |
US20140358304A1 (en) * | 2013-06-03 | 2014-12-04 | Tescom Corporation | Method and Apparatus for Managing Fluid Supply in a Process Control System |
WO2015116615A1 (en) * | 2014-01-28 | 2015-08-06 | Tescom Corporation | Electronic controller with integral vent valve |
US20180119843A1 (en) * | 2014-01-07 | 2018-05-03 | Sundew Technologies, Llc | Fluid-actuated flow control valves |
US11175682B2 (en) * | 2019-07-09 | 2021-11-16 | KLÉRYSTON Lasiê SEGAT | Adjustment and remote control system with a pressure regulator for irrigation systems |
CN116906451A (en) * | 2023-09-07 | 2023-10-20 | 山东大学 | Prepressing self-adjusting differential feedback flow controller and static pressure equipment |
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US6866061B2 (en) * | 2001-09-24 | 2005-03-15 | Hydrogenics Corporation | Back pressure valve with dynamic pressure control |
DE20204532U1 (en) * | 2002-03-21 | 2002-06-13 | Huang Chun Cheng | Electromagnetic pressure differential valve |
JP2004319413A (en) * | 2003-04-21 | 2004-11-11 | Aisan Ind Co Ltd | Gas pressure reducing device of fuel cell system |
JP2006058201A (en) * | 2004-08-23 | 2006-03-02 | Gas Mitsukusu Kogyo Kk | Heat conduction type gas analyzer |
US7384453B2 (en) * | 2005-12-07 | 2008-06-10 | Schlumberger Technology Corporation | Self-contained chromatography system |
ITRM20110203A1 (en) * | 2011-04-21 | 2012-10-22 | Icomet Spa | REDUCER PRESSURE REGULATOR FOR METHANE SUPPLY OR OTHER SIMILAR COMBUSTIBLE FUELS OF INTERNAL COMBUSTION ENGINES |
WO2012151113A1 (en) * | 2011-05-03 | 2012-11-08 | Bp Corporation North America Inc. | Subsea pressure control system |
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RU2530179C1 (en) * | 2013-05-14 | 2014-10-10 | Открытое акционерное общество "Научно-Производственное предприятие "РЕСПИРАТОР" | Reducer and gas flow regulation method |
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Cited By (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6813943B2 (en) * | 2003-03-19 | 2004-11-09 | Mks Instruments, Inc. | Method and apparatus for conditioning a gas flow to improve a rate of pressure change measurement |
US20040182148A1 (en) * | 2003-03-19 | 2004-09-23 | Smith John A. | Method and apparatus for conditioning a gas flow to improve a rate of pressure change measurement |
US20050279408A1 (en) * | 2004-06-18 | 2005-12-22 | Henderson Robert C | Electronically controlled back pressure regulator |
US7258132B2 (en) * | 2004-06-18 | 2007-08-21 | Agilent Technologies, Inc. | Electronically controlled back pressure regulator |
WO2007131346A1 (en) * | 2006-05-11 | 2007-11-22 | Delaney Machinerie Inc. | Pressure controller device |
US9223316B2 (en) | 2007-03-24 | 2015-12-29 | Schlumberger Technology Corporation | Backflow and flow rate control valve |
GB2447862A (en) * | 2007-03-24 | 2008-10-01 | Schlumberger Holdings | Control valve |
GB2447862B (en) * | 2007-03-24 | 2009-10-14 | Schlumberger Holdings | Backflow and flow rate control valve |
US20100043887A1 (en) * | 2007-03-24 | 2010-02-25 | Schlumberger Technology Corporation | Backflow and flow rate control valve |
US20100090137A1 (en) * | 2008-10-10 | 2010-04-15 | Ckd Corporation | Flow rate control device |
US20100108923A1 (en) * | 2008-11-04 | 2010-05-06 | Abb Technology Ag | Electropneumatic transducer with a pneumatic pressure-regulating valve |
US20140358304A1 (en) * | 2013-06-03 | 2014-12-04 | Tescom Corporation | Method and Apparatus for Managing Fluid Supply in a Process Control System |
US20180119843A1 (en) * | 2014-01-07 | 2018-05-03 | Sundew Technologies, Llc | Fluid-actuated flow control valves |
US10465817B2 (en) * | 2014-01-07 | 2019-11-05 | Sundew Technologies, Llc | Fluid-actuated flow control valves |
CN104881057A (en) * | 2014-01-28 | 2015-09-02 | 泰思康公司 | Electronic controller with integral vent valve |
WO2015116615A1 (en) * | 2014-01-28 | 2015-08-06 | Tescom Corporation | Electronic controller with integral vent valve |
US9624947B2 (en) | 2014-01-28 | 2017-04-18 | Tescom Corporation | Electronic controller with integral vent valve |
US11175682B2 (en) * | 2019-07-09 | 2021-11-16 | KLÉRYSTON Lasiê SEGAT | Adjustment and remote control system with a pressure regulator for irrigation systems |
CN116906451A (en) * | 2023-09-07 | 2023-10-20 | 山东大学 | Prepressing self-adjusting differential feedback flow controller and static pressure equipment |
CN116906451B (en) * | 2023-09-07 | 2023-12-05 | 山东大学 | Prepressing self-adjusting differential feedback flow controller and static pressure equipment |
Also Published As
Publication number | Publication date |
---|---|
DE69915374D1 (en) | 2004-04-08 |
EP1151364B1 (en) | 2004-03-03 |
NL1010815C2 (en) | 2000-06-19 |
WO2000036482A1 (en) | 2000-06-22 |
DE69915374T2 (en) | 2005-01-13 |
JP2002532800A (en) | 2002-10-02 |
AU1897300A (en) | 2000-07-03 |
EP1151364A1 (en) | 2001-11-07 |
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